A 100 kg car starting from rest runs down a 30o slope. If the total length of the slope is 20 m, the speed of the car at the bottom, ignoring friction, is:
Correct answer: D. 14 m/sec
- A. 14000 √3 m/sec
- B. 20 sin 30o m/sec
- C. 1.4 m/sec
- D. 14 m/sec
Explanation
h/20=sin 30o => h=20sin30o = 20(0.5) =10mBy law of conservation of energyGain in K.E = Loss in Gravitational P.E1/2mv2 = mghv2 = 2ghv2 = 2(10)(10)v = 14m/s
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Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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